Array Mission Study Guide
ARRAY MISSION STUDY GUIDE
Equal Groups • Arrays • Multiplication & Division
Name:
Date:
RULE 1
The 3 Big Parts of Equal Groups
Groups × Size = Total
Multiplication is fast addition of equal groups. Every equal group story has three numbers:
1. Number of Groups
How many sets or containers?
Example: 4 bowls, 4 bags, 4 boxes
2. Group Size
How many in EACH group?
Example: 3 fish in each bowl
3. Total Amount
How many in all?
Example: 12 fish altogether
4 equal groups of 3
=
Repeated Addition: 3 + 3 + 3 + 3 = 12
Multiplication: 4 × 3 = 12
RULE 2
Arrays: Rows & Columns
Rows (Across) × Columns (Down) = Total
3 Rows (↔ Horizontal) 5 Columns (↕ Vertical)
● ● ● ● ●
● ● ● ● ●
● ● ● ● ●
3 rows of 5 = 3 × 5 = 15
Turn-Around Rule (Commutative)
You can turn an array sideways! The factors switch order, but the total stays the exact same:
3 × 5 = 15 and 5 × 3 = 15
Memory Trick:
Rows go side-to-side like rowboats on water. Columns stand tall like pillars holding up a building.
RULE 3
Multiplication & Division Work Together!
Fact Families
Multiplication
Puts equal groups together to find the unknown total.
Part × Part = TOTAL
Fact Family
18
3
6
Total ALWAYS goes at the top!
Division
Splits a known total apart into equal parts.
TOTAL ÷ Part = Part
4 Related Facts: 3 × 6 = 18 | 6 × 3 = 18 | 18 ÷ 3 = 6 | 18 ÷ 6 = 3
Array Mission Study Guide • Page 1 of 2 Remember: Always identify the TOTAL first!
PART 2
SOLVING FOR MISSING PARTS
Test Strategy & Practice
Case A Fair Sharing
Missing Group Size (? in each)
You know the Total and the Number of Groups. You need to find how many go into each group!
"Leo has 20 pencils. He puts them equally into 4 cups. How many pencils are in each cup?"
4 × ? = 20 or 20 ÷ 4 = ?
1 Draw 4 circles (the cups/groups).
2 Deal 20 tally marks out "one-by-one" until you reach 20.
3 Count 1 group: 5 pencils in each cup!
Case B Grouping / Repeated Subtraction
Missing Groups (? groups)
You know the Total and the Group Size. You need to find how many groups you can make!
"Maya has 24 cookies. She puts 6 cookies in each bag. How many bags can she fill?"
? × 6 = 24 or 24 ÷ 6 = ?
1 Count by 6s up to 24: 6, 12, 18, 24 (4 counts).
2 OR subtract 6 repeatedly: 24 - 6 - 6 - 6 - 6 = 0.
3 Count the sets: Maya can make 4 bags!
WORD PROBLEM DETECTIVE CLUES
Words like "each", "per", and "equal shares" tell you about group size. Words like "in all" or "altogether" tell you the total!
TRY IT!
Pre-Test Quick Check
Solve before tomorrow's assessment!
1. Array Equation
An array has 4 rows and 6 columns. Write two multiplication equations for it:
____ × ____ = ____ ____ × ____ = ____
2. Missing Group Size
Sam has 28 crayons shared equally among 7 boxes. How many in each box?
Equation: 28 ÷ 7 = ____
Answer: ____ crayons in each box
3. Missing Groups
There are 35 soccer players. Each team needs 5 players. How many teams can form?
Equation: ____ × 5 = 35
Answer: ____ teams
4. Fact Family Complete
Write the related division fact for 8 × 4 = 32:
____ ÷ ____ = ____
Array Mission Study Guide • Page 2 of 2 Good luck on tomorrow's assessment! You've got this! ★
